Noob SnG question (Pac $2): Heads-up play

[AKQJ10]

OK, recent consensus (of two) seemed to that we should post beginner questions that could also go to other forums. I may as well get the ball rolling. I'm pretty new to sit-and-gos, I've played maybe dozens over my lifetime, but I don't really feel that I know when I've made a good or bad play like in LHE. And I really don't feel at home heads-up -- who does? -- but I've generally held my own just by turning up the aggresiveness.

Because this is Pac i'm transcribing this by hand. We'd gone back and forth before this hand (having started HU at 4000 to 4000), and I'm afraid I semi-tilted to get a quick result.

Villain: T4150
Hero: T3850

Villain posts T50 on button
Hero posts T100

Hero dealt Ks 9s

Villain raises to T600
Hero reraises to T1700
Villain calls

Flop: 3c 9d Qc (Pot: T3400)

Hero all-in for T2150

Rest in white
<font color="white">
Villain calls
Turn: 3h
River: As
Villain shows Qs Js to win
</font>

HU play totally confuses me so I pretty much go by my gut; I'd rather understand the RIGHT way to play a hand like this. I probably was too aggressive preflop, but I didn't really think he had a hand better than mine (and he didn't, in showdown terms). I think my push with middle pair is somewhat defensible. By that point it's 2/3 of the pot anyway.

Comments, anyone?